Accompanying the progress and the development of a digital-signal-processing technology, in recent years, a recording apparatus and a recording medium, which are used for digitally recording information, have been becoming popular. By using such a recording apparatus and such a recording medium, recording and reproduction processes can be carried out repeatedly without deteriorating qualities of pictures, sounds and the like. Since digital data can be copied as many times as required by sustaining its picture and sound qualities, it is quite within the bounds of possibility that a recording medium containing illegal copies is put in the market. If recording media containing illegal copies are put in the market, the interests of owners of copyrights of various contents such as music and movies and the interests of owners of marketing rights of the contents are infringed. At the present time, in order to avoid such illegal copies of digital data, there has been implemented or proposed a variety of processing systems for preventing illegal copies in digital recording apparatus and digital recording media.
In order to avoid an illegal copy of contents, copy control information provided for the contents is used. Representative examples of the copy control information are an SCMS (Serial Copy Management System) and a CGMS (Copy Generation Management System). These pieces of copy control information prescribe copy status such as Copy Free meaning that data including this copy control information can be copied without restrictions, One Generation Copy Allowed meaning that only a generation of data including this copy control information can be copied and Copy Prohibited meaning that data including this copy control information cannot be copied at all.
The CGMS applied to analog video signals is referred to as a CGMS-A. In accordance with the CGMS-A, in the case of a transmitted NTSC signal, for example, 2 bit information for copy control is included as superposed information in 20-bit additional information superposed on a valid video portion of a specific horizontal segment in a vertical blanking period of a luminance signal of the NTSC signal. The specific horizontal segment is the 20th horizontal segment of the vertical blanking period. On the other hand, the CGMS applied to digital video signals is referred to as a CGMS-D. In accordance with the CGMS-D, 2-bit information for copy control is additional information inserted into digital video data to be transmitted.
The 2-bit information for copy control in the CGMS is referred to hereafter as CGMS information having values of 00 representing Copy Free meaning that data including this copy control information can be copied without restrictions, 10 representing One Generation Copy Allowed meaning that only a generation of data including this copy control information can be copied and 11 representing Copy Prohibited meaning that data including this copy control information cannot be copied at all.
If the CGMS information added to video information has a value of 10, a recording apparatus conforming to the CGMS interprets the video information as information that can be copied and, thus, copies the video information. However, the apparatus conforming to the CGMS adds CGMS information renewed to a value of 11 to recorded video information obtained as a result of the copy operation. If the CGMS information added to video information to be copied has a value of 11, on the other hand, an apparatus conforming to the CGMS interprets the video information as information that cannot be copied at all and, thus, cancels an operation to copy the video information. There has been proposed a method for protecting a copyright by using the CGMS information of a video signal in an IEEE-1394 interface, which is used as an interface for the video signal.
In addition, in the case of an MD (trademark) apparatus where the MD is an abbreviation of a MiniDisc, as a method for preventing illegal copies, an SCMS (Serial Copy Management System) is adopted. The SCMS is a system in which an SCMS signal is output from a digital interface (DIF) of a data reproduction apparatus along with audio data and a data-recording apparatus controls a process to record the audio data on the basis of the SCMS signal received from the data reproduction apparatus.
To put it concretely, the SCMS signal is a signal revealing status of Copy Free meaning that the audio data associated with this SCMS signal can be copied any number of times, status of Copy Once Allowed meaning that the audio data associated with this SCMS signal can be copied only once or status of Copy Prohibited meaning that the audio data associated with this SCMS signal cannot be copied at all. When the data-recording apparatus receives the audio data from the DIF of the data reproduction apparatus, the data-recording apparatus detects the SCMS signal transmitted along with the audio data. If the SCMS signal reveals the status of Copy Free, the audio data and the SCMS signal are recorded onto a MiniDisc. If the SCMS signal reveals status of Copy Once Allowed, the SCMS signal is changed to indicate the status of Copy Prohibited before the audio data and the changed SCMS signal are recorded onto a MiniDisc. If the SCMS signal reveals the status of Copy Prohibited, the audio data and the SCMS signal are not recorded onto a MiniDisc. By executing the control according to the SCMS in this way, it is possible to prevent audio data protected by a copyright as indicated by an SCMS signal from being copied illegally.
As a concrete implementation of the copy control information described above, there has been provided CCI (Copy Control Information) prescribed by 5C-DTCP (5 Companies' Digital Transmission Content Protection) specifications proposed jointly by five companies including Sony Corporation, which is the applicant for a patent of the present invention. The 5C-DTCP specifications prescribe a method of transmitting CCI (Copy Control Information) for contents transmitted through an IEEE-1394 interface, contents transmitted as a satellite digital TV broadcast, contents transmitted as a ground-wave digital TV broadcast and the like. In addition, the 5C-DTCP specifications also prescribe copy control processing in a recording/reproduction apparatus for recording and reproducing such contents.
Furthermore, besides the methods described above, there is also a system for adding copy control information to transmitted contents as a digital watermark (WM). Superposed to contents, which can be picture or audio data, a digital watermark (WM) is information difficult to see or sense in a normal reproduced state of the contents. Copy control of contents is then executed by detection of a digital watermark from the contents during typically an operation to record or reproduce the contents. Even in the case of analog contents, a digital watermark can be detected and embedded from and into the contents, widening the range of applications of the digital watermark. However, there is required a configuration used specially for detecting and embedding a digital watermark from or into the contents.
As described above, there is a number of methods for adding copy control information, which is intended for protection of a copyright of contents, to the contents. By the same token, there is a great variety of recording/reproduction apparatus including apparatus capable of processing the various kinds of copy control information described above and apparatus incapable of processing the copy control information.
In the present state of coexistence of various apparatus, there are cases in which operations to input contents from apparatus, output contents to apparatus and copy contents between apparatus entail difficulties in correctly handling copy control information of the contents. For execution of a process of contents including both additional copy control information using a digital watermark (WM) and the additional CCI (Copy Control Information) proposed by the 5C-DTCP (5 Companies' Digital Transmission Content Protection) system described above, for example, there are several types of apparatus including a contents-processing apparatus incapable of detecting a digital watermark (WM) from contents, a contents-processing apparatus capable of detecting a digital watermark (WM) from contents but incapable of embedding a digital watermark (WM) into contents and a contents-processing apparatus capable of both detecting a digital watermark (WM) from contents and embedding a digital watermark (WM) into contents. Thus, processes to fetch and renew the copy control information using a digital watermark (WM) and the CCI (Copy Control Information) are carried out in a way varying from apparatus to apparatus. In a consequence, there is resulted in a situation in which an accurate process to update the copy control information using a digital watermark (WM) and the CCI (Copy Control Information) cannot be carried out.
For example, there are an apparatus, which renews the CCI in accordance with a detected value of the digital watermark (WM), an apparatus, which merely renews the CCI without acquiring a detected value of the digital watermark (WM), and an apparatus, which renews both the CCI and the digital watermark (WM). Thus, different processes are carried out in accordance with the capability of the apparatus. As a result, there is raised a problem of a mismatch between the CCI and the WM, making it impossible to execute correct copy control.
In addition, there is also raised a demand for imposition of a restriction on the output of contents recorded on a recording medium in dependence on the original input source of the recorded contents. In such a case, if information on the input source is lost, it is impossible to accurately impose a reproduction restriction prescribed in accordance with the input source in advance. As a result, it is quite within the bounds of possibility that operations to reproduce and copy contents are carried out not in an orderly manner.